First of all, the exFAT update is so super minimal and easy that there is literally no reason
not to do it. Second, any
true homebrew support is going to come much much later and refusing to update now just means you'll find yourself being forced to upgrade very soon when some game or other comes out and requires it that you want to play. Any exploits right now are going to be much too minimal to be of any real use unless you want to basically just not even actually own your own Switch. (Seriously, if you want to keep one never updated you need to just go buy another so you can actually use the equipment you paid for because otherwise you're going to end up with it just lying around on a shelf gathering dust doing nothing for about two years in reality and then you'll take it out and update it so you can use a modern exploit...)
But more importantly, since you're pretty determined here to pretend you'll have real homebrew if you're stubborn enough to hold to an old version, when (not if. When.) you have to update to a modern filesystem that supports things like large files among other things, you'll suddenly find you must manually move a humongous amount of data off of the card onto your PC, format, and then move it all back over again (which also means you'll need enough free space.) If the 3DS is any indicator here, I can assure you that you'll be looking at a process of several hours probably. If you're lucky. Nintendo isn't afraid to use an inordinate amount of very tiny files. And, of course, if you're using an external drive or something you can probably count on a bit more latency added each time slowing the process even more. I'm sure someone will throw in something large because, well, why not, but the general policy basically makes transferring data from one card to another or reformatting such an incredible pain in the rear you really kind of want to only have to do this once. I'd be willing to bet the Switch is actually going to be even worse about it compared to the 3DS as games use much more data which probably isn't likely to result in simply using larger files. (Actually, combined data files don't have much of an advantage on a solid state storage medium -- it's actually more work if anything. So keeping data separate is actually advantageous in a medium with effectively zero seek latency.)
Honestly, right now the only value of any sort of hacks and exploits isn't even for us. The
real value of such things is for those who actually do the hacking to use this to get into the system and learn its inner workings early on. This won't do
you any good right now, but it will mean that true hacks come sooner rather than later. We're probably still looking at a year or two before it gets hacks that are actually worth using. This is not the Wii/Wii-U. This is a different system that works in a different way and will have to be hacked differently.
i want a big sd card but they are so damn overpriced
Er, no they're not. You're looking in places like Amazon, right? If you go to a local retailer you'll get ripped off unless you get an uber-cheap low quality generic (and even then the price is still a bit ridiculous) but on Amazon you can get a 128GB for $40 or so. That's 34 cents per gigabyte... It's cheaper for smaller, but I'm guesstimating that 128GB will, in the long run, be about the optimal size for the Switch.